U.S. patent application number 15/775083 was filed with the patent office on 2018-11-08 for decorative article featuring a microscopic periodic pattern and methods of making the same.
The applicant listed for this patent is 3M INNOVATIVE PROPERTIES COMPANY. Invention is credited to John C. Clark, Samad Javid, Vivek Krishnan, Alexander J. Kugel, Aaron K. Nienaber, Chris A. Pommer, Christopher B. Walker, JR..
Application Number | 20180319204 15/775083 |
Document ID | / |
Family ID | 57796980 |
Filed Date | 2018-11-08 |
United States Patent
Application |
20180319204 |
Kind Code |
A1 |
Clark; John C. ; et
al. |
November 8, 2018 |
Decorative Article Featuring a Microscopic Periodic Pattern and
Methods of Making the Same
Abstract
Described herein is decorative article having a coefficient of
friction less than 0.3 wherein the decorative articles comprises:
(i) a microsphere layer comprising a plurality of microspheres,
wherein the microsphere layer comprises a monolayer of microspheres
and wherein the plurality of microspheres are in a microscopic
periodic pattern; and (ii) a bead bonding layer disposed on the
microsphere layer, wherein the plurality of microspheres are
partially embedded in the bead bonding layer. Also disclosed herein
are transfer articles and methods of making the decorative articles
and transfer articles.
Inventors: |
Clark; John C.; (Maplewood,
MN) ; Javid; Samad; (Woodbury, MN) ; Krishnan;
Vivek; (St. Paul, MN) ; Kugel; Alexander J.;
(Woodbury, MN) ; Nienaber; Aaron K.; (Maplewood,
MN) ; Pommer; Chris A.; (Woodbury, MN) ;
Walker, JR.; Christopher B.; (St. Paul, MN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
3M INNOVATIVE PROPERTIES COMPANY |
St. Paul |
MN |
US |
|
|
Family ID: |
57796980 |
Appl. No.: |
15/775083 |
Filed: |
December 14, 2016 |
PCT Filed: |
December 14, 2016 |
PCT NO: |
PCT/US2016/066471 |
371 Date: |
May 10, 2018 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62269413 |
Dec 18, 2015 |
|
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|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B44C 1/1756 20130101;
B44C 1/1725 20130101; B32B 37/025 20130101; B44C 1/18 20130101;
B32B 2451/00 20130101; B32B 7/12 20130101; B32B 2307/418 20130101;
B32B 5/16 20130101 |
International
Class: |
B44C 1/18 20060101
B44C001/18; B44C 1/17 20060101 B44C001/17; B44C 1/175 20060101
B44C001/175; B32B 5/16 20060101 B32B005/16; B32B 7/12 20060101
B32B007/12; B32B 37/00 20060101 B32B037/00 |
Claims
1. A decorative article comprising: a microsphere layer comprising
a plurality of microspheres, wherein the microsphere layer
comprises a monolayer of microspheres and wherein the plurality of
microspheres are in a microscopic periodic pattern; and a bead
bonding layer disposed on the microsphere layer, wherein the
plurality of microspheres are partially embedded in the bead
bonding layer; and wherein the plurality of microspheres has a
ratio of microsphere height to microsphere center-to-center
distance greater than 0.1 and less than 0.5, and wherein the
decorative article has a coefficient of friction less than 0.3 as
measured by the Method for Coefficient of Friction Testing.
2. The decorative article of claim 1, wherein the plurality of
microspheres covers more than 10% and less than 50% of the surface
of the bead bonding layer,
3. A decorative article comprising: a microsphere layer comprising
a plurality of microspheres, wherein the microsphere layer
comprises a monolayer of microspheres and wherein the plurality of
microspheres are in a microscopic periodic pattern; and a bead
bonding layer disposed on the microsphere layer, wherein the
plurality of microspheres are partially embedded in the bead
bonding layer; and wherein the plurality of microspheres covers
more than 10% and less than 50% of the surface of the bead bonding
layer, and wherein the decorative article has a coefficient of
friction less than 0.3 as measured by the Method for Coefficient of
Friction Testing.
4. The decorative article of claim 3, wherein the plurality of
microspheres has a ratio of microsphere height to microsphere
center-to-center distance greater than 0.1 and less than 0.5
5. The decorative article of claim 1, wherein the plurality of
microspheres covers more than 20% and less than 30% of the surface
of the bead bonding layer.
6. The decorative article of claim 1, wherein the distance between
nearest neighbors in plurality of microspheres is 1/8 to 5 times
the average diameter of the microspheres.
7. The decorative article of claim 1, wherein the microspheres in
the plurality of microspheres have an index of refraction of less
than 1.55.
8. The decorative article of claim 1, wherein the monolayer of
microspheres further comprises a macroscopic pattern.
9. A transfer article comprising: a support layer; a transfer
polymer layer bonded to the support layer; and a microsphere layer
comprising a plurality of microspheres, wherein the microsphere
layer comprises a monolayer of microspheres and wherein the
plurality of microspheres are in a microscopic periodic pattern;
and wherein the plurality of microspheres are partially embedded in
the transfer polymer layer such that more than 50% of the average
diameter of the microspheres is exposed and the plurality of
microspheres covers more than 10% and less than 50% of the surface
of the transfer polymer layer.
10. A transfer article comprising: a support layer; a transfer
polymer layer bonded to the support layer; and a microsphere layer
comprising a plurality of microspheres, wherein the microsphere
layer comprises a monolayer of microspheres and wherein the
plurality of microspheres are in a microscopic periodic pattern;
and wherein the plurality of microspheres are partially embedded in
the transfer polymer layer such that more than 50% of the average
diameter of the microspheres is exposed and wherein the plurality
of microspheres has a ratio of microsphere height to microsphere
center-to-center distance greater than 0.1 and less than 0.5.
11. A method of making a decorative article, the method comprising:
spatially orienting a plurality of microspheres in a layer, such
that the plurality of microspheres has a microscopic periodic
pattern; embedding the layer of microspheres in a transfer polymer;
contacting the embedded layer of microspheres with a bead bonding
layer; and removing the transfer polymer to form the decorative
article of claim 1.
12. A method of making the decorative article of any one of claims
1-8, comprising: depositing a barrier layer material in a
predetermined pattern onto a first major surface of a support to
form a patterned barrier layer; contacting a plurality of
microspheres onto the patterned barrier layer to form a patterned
microsphere layer; contacting the patterned microsphere layer with
a transfer polymer and removing the support to form an embedded
layer of microspheres comprising a plurality of microspheres
partially embedded in the transfer polymer with the apexes of the
microspheres exposed; contacting the exposed apex side of the
embedded layer of microspheres with a bead bonding layer; and
separating the bead bonding layer from the transfer polymer to form
the decorative article of claim 1.
13. A method of making the decorative article of claim 1,
comprising: depositing a barrier layer material in a predetermined
pattern onto a first major surface of a support to form a patterned
barrier layer; contacting a plurality of microspheres onto the
patterned barrier layer to form a patterned microsphere layer;
contacting the patterned microsphere layer with a bead bonding
layer; and removing the support to make the decorative article of
any one of claims 1-8.
14. A method of making the decorative article of claim 1,
comprising: providing a production tool having a plurality of
cavities, wherein the plurality of cavities are in a predetermined
pattern; contacting a plurality of microspheres to the production
tool such that the plurality of cavities are filled with the
plurality of microspheres to form a layer of patterned
microspheres; transferring the layer of patterned microspheres to a
transfer polymer to form an embedded layer of microspheres
comprising a plurality of microspheres partially embedded in the
transfer polymer with the apexes of the microspheres exposed;
contacting the exposed apex side of the embedded layer of
microspheres with a bead bonding layer; and separating the bead
bonding layer from the transfer polymer to form the decorative
article of claim 1.
15. A method of making the decorative article of claim 1,
comprising: providing a production tool having a plurality of
cavities, wherein the plurality of cavities are in a predetermined
pattern; contacting a plurality of microspheres to the production
tool such that the plurality of cavities are filled with the
plurality of microspheres to form a layer of patterned
microspheres; transferring the layer of patterned microspheres to a
bead bonding layer to form an embedded layer of microspheres
comprising a plurality of microspheres partially embedded in the
bead bonding layer to make the decorative article of claim 1.
16. The decorative article of claim 1, wherein the microscopic
periodic pattern comprises a repeat unit selected from at least one
of triangular, quadrilateral, pentagonal, hexagonal, or
combinations thereof.
17. The decorative article of claim 1, further comprising a
substrate, wherein the bead bonding layer is disposed between the
substrate and the microsphere layer.
18. The decorative article of claim 1, wherein the microspheres in
the plurality of microspheres are translucent or opaque.
19. The decorative article of claim 1, wherein the microspheres in
the plurality of microspheres have a Knoop hardness of 1300
kg/m.sup.2.
20. The decorative article of claim 1, wherein the plurality of
microspheres are partially embedded to at least 60% of the
microsphere diameter in the bead bonding layer.
Description
TECHNICAL FIELD
[0001] A decorative article comprising a monolayer of microspheres
arranged in a microscopic periodic pattern atop a bead bonding
layer is described.
DESCRIPTION OF THE FIGURES
[0002] FIG. 1 is a cross-sectional view of a decorative article
according to one embodiment of the present disclosure;
[0003] FIG. 2 is a schematic representation of the top view of the
decorative article made according the EX1A;
[0004] FIGS. 3A and 3B are exemplary microscopic periodic
patterns;
[0005] FIG. 4 is a top view of a decorative article comprising a
macroscopic pattern made from a microscopic periodic pattern of
microspheres; and
[0006] FIG. 5 is a cross-sectional view of a transfer article
according to one embodiment of the present disclosure.
SUMMARY
[0007] There is a need for microsphere coated articles and transfer
articles that provide improvements in cutting and/or cost
reduction, while achieving the surface durability (i.e., scratch
and/or abrasion) and wear resistance provided by conventional
microsphere coated articles and transfer articles.
[0008] In one aspect, a decorative article is provided comprising:
a microsphere layer comprising a plurality of microspheres, wherein
the microsphere layer comprises a monolayer of microspheres and
wherein the plurality of microspheres are in a microscopic periodic
pattern; and a bead bonding layer disposed on the microsphere
layer, wherein the plurality of microspheres are partially embedded
in the bead bonding layer; and wherein the plurality of
microspheres has a ratio of microsphere height to microsphere
center-to-center distance greater than 0.1 and less than 0.5, and
wherein the decorative article has a coefficient of friction less
than 0.3 as measured by the Method for Coefficient of Friction
Testing.
[0009] In one aspect, a decorative article is provided comprising:
a microsphere layer comprising a plurality of microspheres, wherein
the microsphere layer comprises a monolayer of microspheres and
wherein the plurality of microspheres are in a microscopic periodic
pattern; and a bead bonding layer disposed on the microsphere
layer, wherein the plurality of microspheres are partially embedded
in the bead bonding layer; and wherein the plurality of
microspheres covers more than 10% and less than 50% of the surface
of the bead bonding layer, and wherein the decorative article has a
coefficient of friction less than 0.3 as measured by the Method for
Coefficient of Friction Testing.
[0010] In another aspect, a transfer article is described
comprising: a support layer; a transfer polymer layer bonded to the
support layer; and a microsphere layer comprising a plurality of
microspheres, wherein the microsphere layer comprises a monolayer
of microspheres and wherein the plurality of microspheres are in a
microscopic periodic pattern; and wherein the plurality of
microspheres are partially embedded in the transfer polymer layer
such that more than 50% of the average diameter of the microspheres
is exposed and the plurality of microspheres covers more than 10%
and less than 50% of the surface of the transfer polymer layer.
[0011] In yet another embodiment, a method of making the decorative
article is described, the method comprising:
[0012] spatially orienting a plurality of microspheres in a layer,
such that the plurality of microspheres has a microscopic periodic
pattern;
[0013] embedding the layer of microspheres in a transfer
polymer;
[0014] contacting the embedded layer of microspheres with a bead
bonding layer; and
[0015] removing the transfer polymer to form the decorative
article
[0016] In still another embodiment, a method of making the
decorative article is described, the method comprising:
[0017] depositing a barrier layer material in a predetermined
pattern onto a first major surface of a support to form a patterned
barrier layer;
[0018] contacting a plurality of microspheres onto the patterned
barrier layer to form a patterned microsphere layer;
[0019] contacting the patterned microsphere layer with a polymeric
support, wherein the polymeric support is a bead bonding layer or a
transfer polymer layer to make the decorative article.
[0020] In still another embodiment, a method of making the
decorative article is described, the method comprising:
[0021] providing a production tool having a plurality of cavities,
wherein the plurality of cavities are in a predetermined
pattern;
[0022] contacting a plurality of microspheres to the production
tool such that the plurality of cavities are filled with the
plurality of microspheres to form a layer of patterned
microspheres;
[0023] transferring the layer of patterned microspheres to a
polymeric support, wherein the polymeric support is a bead bonding
layer or a transfer polymer layer to make the decorative
article.
[0024] The above summary is not intended to describe each
embodiment. The details of one or more embodiments of the invention
are also set forth in the description below. Other features,
objects, and advantages will be apparent from the description and
from the claims.
DETAILED DESCRIPTION
[0025] As used herein, the term
[0026] "a", "an", and "the" are used interchangeably and mean one
or more; and
[0027] "and/or" is used to indicate one or both stated cases may
occur, for example A and/or B includes, (A and B) and (A or B).
[0028] Also herein, recitation of ranges by endpoints includes all
numbers subsumed within that range (e.g., 1 to 10 includes 1.4,
1.9, 2.33, 5.75, 9.98, etc.).
[0029] Also herein, recitation of "at least one" includes all
numbers of one and greater (e.g., at least 2, at least 4, at least
6, at least 8, at least 10, at least 25, at least 50, at least 100,
etc.).
[0030] Decorative protective surfaces find many consumer
applications. Household appliances, automotive interiors and
paints, consumer electronic devices, such as laptops and hand held
devices, are all examples where consumers prefer materials that
deliver considerable protection from scratches, wear and abrasion
while retaining high cosmetics and aesthetics through the
material's lifecycle. Low gloss matte surfaces are of particular
interest to many consumers because of their aesthetic appeal.
[0031] Durable decorative laminates and films comprised of glass
beads are broadly known. These low gloss constructions typically
consist of exposed glass bead surfaces that impart high durability
and decorative properties to the construction. Typically, the beads
are cascade coated or otherwise applied, such that they form a
continuous monolayer across the article surface, wherein the beads
are packed closely. See U.S. Pat. Nos. 4,849,265 (Ueda et al.) and
5,620,775 (LaPerre). Because these constructions comprise hard
beads for durability, and the beads are random and closely packed
along the construction's surface, cutting the constructions can be
difficult.
[0032] By reducing the surface coverage of the beads, the
constructions may be easier to cut, however, if the beads are
randomly applied, the beads can cluster either by random or by
electrostatic attractions, leaving areas on the construction's
surface void of beads. The present application has identified
ordered surfaces that comprise less than full coverage of beads
while still providing the surface durability and wear resistance of
the underlying surface similar to that provided by conventional,
continuous monolayer bead-coated constructions.
[0033] Disclosed herein is a construction, which has an exposed
surface having a microscopic periodic pattern, wherein the surface
has mechanical durability (e.g., abrasion resistant and/or pencil
hardness) and the ability to be more easily cut and/or is less
expensive than similar constructions that do not have the
microscopic periodic pattern. These constructions, in one
embodiment, may be applied to surfaces to alter the properties of
the surface.
[0034] In one embodiment, the decorative articles as disclosed
herein have a coefficient of retroreflection of less than or equal
to 1.0 candelas/lux/square meter. In some preferred embodiments,
the presently disclosed articles have a coefficient of
retroreflection of less than or equal to 0.5 candelas/lux/square
meter. In some more preferred embodiments, the presently disclosed
articles have a coefficient of retroreflection of less than or
equal to 0.1 candelas/lux/square meter.
[0035] FIG. 1 is an illustration of a cross-section of one
embodiment of the decorative article of the present disclosure.
Decorative article 10 comprises a microsphere layer which comprises
a monolayer of microspheres 11, wherein the plurality of
microspheres are partially embedded into bead bonding layer 12. In
one embodiment, the decorative article comprises the plurality of
microspheres embedded in the bead bonding layer. In another
embodiment, the decorative article comprises the plurality of
microspheres embedded in the bead bonding layer and the bead
bonding layer disposed on a substrate surface. Such as construction
is shown in FIG. 1 where bead bonding layer 12 is disposed on
substrate 13. The substrate layer may provide additional support to
the bead bonding layer and embedded microspheres during processing
and handling. Alternatively or additionally, the substrate layer
may be the surface the decorative article protects from abrasion,
scratches, etc.
[0036] Substrate Layer
[0037] Examples of suitable substrate layers include but are not
limited to those selected from at least one of fabrics (including
synthetics, non-synthetics, woven and non-woven such as nylon,
polyester, etc.), polymer coated fabrics such as vinyl coated
fabrics, polyurethane coated fabrics, etc.; leather; metal; paint
coated metal; paper; polymeric films or sheets such as polyethylene
terephthalate, acrylics, polycarbonate, polyurethane, elastomers
such as natural and synthetic rubber, and the like; and open-cell
foams and closed cell foams, including for example, polyurethane
foam, polyethylene foam, foamed rubber, and the like. The
substrates may, for example, be in the form of a clothing article
or footwear; automobile, marine, or other vehicle seat coverings;
automobile, marine, or other vehicle bodies; orthopedic devices;
electronic devices (including, for example, track pads, and outer
surface cover), hand held devices, household appliances; sporting
goods; and the like.
[0038] In one embodiment, the substrate has a thickness of at least
5, 10, 20, 25, 50 or even 75 micrometers. In one embodiment, the
substrate has a thickness of at most 25 mm or even 50 mm
[0039] Bead Bonding Layer
[0040] The plurality of microspheres are held in place on top of
the substrate via a bead bonding layer. The bead bonding layer is
typically an organic polymeric material. It should exhibit good
adhesion to the microspheres. It is also possible that an adhesion
promoter for the microspheres could be added directly to the bead
bonding layer itself as long as it is compatible within the process
window for disposing the bead bonding layer on the surfaces of the
microspheres.
[0041] Materials useful in the bead bonding layer include, but are
not limited to those selected from at least one of polyurethanes,
polyesters, acrylic and methacrylic acid ester polymers and
copolymers, epoxies, polyvinyl chloride polymers and copolymers,
polyvinyl acetate polymers and copolymers, polyamide polymers and
copolymers, fluorine containing polymers and copolymers, silicones,
silicone containing copolymers, elastomers, including synthetic and
natural rubbers such as neoprene, acrylonitrile butadiene
copolymers, polymer matrix composites, and combinations thereof. In
some embodiments, the polymer matrix composites include
nanoparticles in resins, fibers in resins, and the like.
Combinations can include any combinations of materials, such as
interpenetrating networks, dual cure systems, and the like.
[0042] The bead bonding layer can be formed, for example, out of
solution, aqueous dispersion, or 100% solids coating such as via
hot melt, extrusion, or reactive coating. The bead bonding layer
may be transparent, translucent, or opaque. It may be colored or
colorless. The bead bonding layer may, for example, be clear and
colorless or pigmented with opaque, transparent, or translucent
dyes and/or pigments. In some embodiments, inclusion of specialty
pigments, such as for example metallic flake pigments, can be
useful.
[0043] In one embodiment, the thickness of the bead bonding layer
is at least 50% of the average diameter of the microspheres.
Exemplary thicknesses for the bead bonding layer include:
thicknesses of at least 10, 25, 50, 100, or even 250 .mu.m
(micrometers) or even more (e.g., at least 1 millimeter, at least 1
centimeter, or even 1 meter).
[0044] Microsphere Layer
[0045] The microsphere layer comprises a plurality of microspheres.
The microspheres useful in the present disclosure comprise glass,
glass ceramics, ceramics, polymers, metals, and combinations
thereof. Glass is an amorphous material, while ceramic refers to a
crystalline or partially crystalline material. Glass ceramics have
an amorphous phase and one or more crystalline phases. These
materials are known in the art.
[0046] The microspheres may comprise oxide materials including:
silicon dioxide, boron oxide, phosphorous oxide, aluminum oxide,
germanium oxide, tin oxide, zinc oxide, bismuth oxide, titanium
oxide, zirconium oxide, lanthanide oxides, barium oxide, strontium
oxide, combinations thereof; and nonoxide materials including
carbide, boride, nitride and silicide, and combinations thereof;
and combinations of oxide and nonoxide materials.
[0047] Exemplary glass types include: soda lime silicate glass,
borosilicate, Z-glass, E-glass, titanate- and aluminate-based
glasses, etc. Exemplary glass-ceramic microspheres include those
based on lithium disilicate.
[0048] In some embodiments, the microspheres are glass beads. The
glass beads are largely spherically shaped. The glass beads are
typically made by grinding ordinary soda-lime glass or borosilicate
glass, typically from recycled sources such as from glazing and/or
glassware. Common industrial glasses could be of varying refractive
indices depending on their composition. Soda lime silicates and
borosilicates are some of the common types of glasses. Borosilicate
glasses typically contain boria and silica along with other
elemental oxides such as alkali metal oxides, alumina etc. Some
glasses used in the industry that contain boria and silica among
other oxides include E glass, and glass available under the trade
designation "NEXTERION GLASS D" from Schott Industries, Kansas
City, Miss., and glass available under the trade designation
"PYREX" from Corning Incorporated, New York, N.Y.
[0049] The grinding process yields a wide distribution of glass
particle sizes. The glass particles are spherodized by treating in
a heated column to melt the glass into spherical droplets, which
are subsequently cooled. Not all the particles are perfect spheres.
Some are oblate, some are melted together and some contain small
bubbles.
[0050] In one embodiment, the microspheres are plastic particles.
The plastic particles selected should comprise a hardness greater
than the substrate surface to protect the underlying substrate
surface. One exemplary plastic particle includes polyurethane,
polystyrene, acrylic and methacrylic acid ester polymers and
copolymers (e.g., poly(methyl methacrylate)), and polyurea
spheres.
[0051] In one embodiment, the microspheres comprise a surface
modification as is known in the art to improve the adhesion to the
bead bonding layer. Such treatments include those selected from the
group consisting of silane coupling agent, titanate,
organo-chromium complex, and the like, to maximize the adhesion of
the microspheres to the first polymer layer. Preferably, the
coupling agent is a silane such as aminosilane, glyoxide silane, or
acrylsilane.
[0052] The treatment level for such coupling agents is on the order
of 50 to 500 parts by weight coupling agent per million parts by
weight microspheres. Microspheres having smaller diameters would
typically be treated at higher levels because of their higher
surface area. Treatment is typically accomplished by spray drying
or wet mixing a dilute solution such as an alcohol solution (such
as ethyl or isopropyl alcohol, for example) of the coupling agent
with the microsphere, followed by drying in a tumbler or auger-fed
dryer to prevent the microspheres from sticking together. One
skilled in the art would be able to determine how to best treat the
microspheres with the coupling agent.
[0053] In one embodiment, the microspheres of the present
disclosure have a Knoop hardness of at least 1,300 kg/mm.sup.2, or
even 1,800 kg/mm.sup.2. The "Knoop hardness" as used herein is an
indentation of microhardness measured by using a Knoop indenter; it
is a value obtained by dividing the applied load with which a
rhombic indentation is formed on the surface of a sample, by the
projected area of the indentation computed from the long diagonal
of the permanent indentation. The method for measuring the Knoop
hardness is described in ASTM C849-88 (2011) "Standard Test Method
for Knoop Indentation Hardness of Ceramic Whitewares".
[0054] The microspheres for use in the present invention are
substantially spherical, for example, having a sphericity of at
least 80%, 85%, or even 90%.
[0055] Preferable examples of the spherical particles include fused
alumina, alumina produced by the Bayer process, zirconia, titania,
and eutectic mixtures thereof.
[0056] As a method for shaping inorganic particles into spherical
ones, it is possible to apply a method in which the above-described
inorganic material in an indeterminate form is ground, and melted
in a high-temperature oven at a temperature above the melting point
thereof, thereby obtaining spherical particles by utilizing the
surface tension; or a method in which the above-described inorganic
material is melted at a high temperature above the melting point
thereof, and the melt is sprayed to obtain spherical particles.
[0057] The microspheres useful in the present disclosure may be
transparent, translucent, or opaque. In one embodiment, the
microspheres have a refractive index of at least 1.5, 1.6, 1.8, 2.0
or even 2.2. In another embodiment, the microspheres have a
refractive index of less than 1.3, 1.4, 1.5, or even 1.55. The
refractive index may be determined by the standard Becke line
method.
[0058] The microspheres are preferably free of defects. As used
herein, the phrase "free of defects" means that the microspheres
have low amounts of bubbles, low amounts of irregular shaped
particles, low surface roughness, low amount of inhomogeneities,
low amounts undesirable color or tint, or low amounts of other
scattering centers.
[0059] In some embodiments, a useful range of average microsphere
diameters is at least 10, 20, 25, 40, 50, 75, 100, or even 150
.mu.m (micrometers); at most 200, 400, 500, 600, 800, 900, or even
1000 .mu.m. The microspheres may have a unimodal or multi-modal
(e.g., a bimodal) size distribution depending on the
application.
[0060] The microspheres are typically sized via screen sieves to
provide a useful distribution of particle sizes. Sieving is also
used to characterize the size of the microspheres. With sieving, a
series of screens with controlled sized openings is used and the
microspheres passing through the openings are assumed to be equal
to or smaller than that opening size. For microspheres, this is
true because the cross-sectional diameter of the microsphere is
almost always the same no matter how it is oriented to a screen
opening.
[0061] In some embodiments, to calculate the "average diameter" of
a mixture of microspheres one would sieve a given weight of
particles such as, for example, a 100 gram sample through a stack
of standard sieves. The uppermost sieve would have the largest
rated opening and the lowest sieve would have the smallest rated
opening. Shown below is table of exemplary sieves.
TABLE-US-00001 TABLE 1 U.S. Sieve Designation No. Nominal Opening
(microns) 80 180 100 150 120 125 140 106 170 90 200 75 230 63 270
53 325 45 400 38 500 25 635 20
[0062] Alternately, average diameter can be determined using any
commonly known microscopic methods for sizing particles. For
example, optical microscopy or scanning electron microscopy, and
the like, can be used in combination with any image analysis
software. For example, software commercially available as free ware
under the trade designation "IMAGE J" from NIH, Bethesda, Md.
[0063] In one embodiment, the plurality of microspheres have a
difference in size distribution not more than 40% (30% or even 20%)
based on the average microsphere diameter.
[0064] Decorative Article
[0065] The decorative articles of the present disclosure, comprise
a plurality of microspheres, which are arranged in a monolayer
(i.e., a single layer) on the surface of the bead bonding layer in
a microscopic periodic pattern, meaning that the microspheres are
arranged in a pattern on the microscopic level (i.e., a pattern in
relation to the other microspheres) and the pattern is periodic
(i.e., not random and having an order to it). The unit repeat,
i.e., the area consuming the repeat pattern may have a triangular,
quadrilateral (e.g., square, rhombus, rectangle, parallelogram),
hexagonal, or other repeat pattern shape, which may be symmetric or
asymmetric in nature.
[0066] Shown in FIG. 2 is a top view of decorative article 20 of
the present disclosure, wherein the plurality of microspheres 22
are arranged in a microscopic periodic pattern across the top of
the article. The microspheres in FIG. 2 are arranged in a
triangular pattern.
[0067] Shown in FIGS. 3A and 3B are top views of a construction
wherein the plurality of microspheres are arranged in a square
(FIG. 3A) and hexagonal (FIG. 3B) pattern.
[0068] In addition to the microscopic patterning, the microspheres
in the layer may comprise a macroscopic pattern. The microscopic
patterning is on the order of the diameter of the microspheres and
the macroscopic pattern is a pattern much larger than the diameter
of the microspheres, for example, 50, or even 100 times larger than
the average diameter of the microspheres. See for example FIG. 4,
where image 46 is a macroscopic pattern made with the microscopic
patterning of a plurality of microspheres 44.
[0069] In the decorative articles of the present disclosure, the
plurality of microspheres are partially embedded into the bead
bonding layer, which means that the microspheres are located
approximately at least 50%, 60%, 70% or even 80% of the microsphere
diameter into the bead bonding layer, however, a portion of each of
the microspheres projects outwardly from the surface of the bead
bonding layer to provide among other things, durability, abrasion
resistance, and/or a low coefficient of friction. Shown in FIG. 1
is "h", which is the vertical height from the surface of the bead
bonding layer to the apex of the microsphere and "ctc" which is the
distance from the apex of one microsphere to the apex of an
adjacent microsphere. By averaging the "h" and "ctc" for the
decorative article, a ratio of microsphere height to microsphere
center-to-center distance can be determined. In one embodiment, the
plurality of microspheres have a ratio of microsphere height to
microsphere center-to-center distance is greater than 0.1, 0.15,
0.2, or even 0.25; and at most 0.3, 0.4, or even 0.5.
[0070] In the present disclosure, the plurality of microspheres
cover more than 10, 15, 20, or even 25%; and less than 30, 40, 45,
or even 50% of the surface of the bead bonding layer.
[0071] In one embodiment, the microspheres do not touch their
neighbor. In fact, in one embodiment, the distance between nearest
neighbors between two microspheres in the plurality of microspheres
is at least 1/8, 1/4, 1/2, 3/4, 1 or even 1.5 times the average
diameter of the microspheres; and at most 3, 3.5, 4, 4.5, or even 5
times the average diameter of the microspheres.
[0072] The decorative article of the present disclosure are
durable, meaning that they have abrasion and/or scratch resistance.
Abrasion resistance, can be measured using a rotary Taber abraser
and visually inspecting the samples for damage. In one embodiment,
the decorative articles of the present disclosure have an abrasion
resistance of no more than 10, 5, or even 3.5. The scratch
resistance can be measured by pencil hardness. In other words, at
which hardness the pencil scratches the surface. In one embodiment,
the decorative articles of the present disclosure have a pencil
hardness value of at least 3H, 6H, 8H, or even 10H at a force of
2.5 Newtons.
[0073] The decorative article of the present disclosure have a
coefficient of friction of less than 0.3 or even 0.2. The
coefficient of friction can be measured by the Method for
Coefficient of Friction Testing disclosed herein.
[0074] Other Layers
[0075] In addition to the substrate, bead bonding layer, and
microsphere layer previously mentioned, the decorative article of
the present disclosure may also comprise additional layers to
impart desirable characteristics into the decorative article. For
example, the decorative article may be made stain resistant, by
using a bead bonding layer comprising a fluorine-containing
polymer, such as those derived from tetrafluoroethylene,
hexaflouropropylene, vinylidene fluoride, etc., as taught in WO
Publ. No. 2014/210249 (Walker et al.), incorporated herein by
reference. A nanoparticle-containing undercoat may be applied
between the microsphere layer and the bead bonding layer to provide
anti-soiling properties as taught in U.S. Pat. Publ. No.
2015-0343502 (Clark et al.), incorporated herein by reference. In
one embodiment, an stain resistant layer is disposed between the
bead bonding layer and the microsphere layer, wherein the stain
resistant layer comprises a resin selected from at least one of the
following thermoplastic and thermoset (i.e., crosslinked)
materials: polyurethanes, polyureas, polyurethane ureas,
polypolyesters, polycarbonate, acrylonitrile butadiene styrene,
polyolefins, acrylic and methacrylic acid ester polymers and
copolymers, polyvinyl chloride polymers and copolymers, polyvinyl
acetate polymers and copolymers, polyamide polymers and copolymers,
fluorine containing polymers and copolymers, silicones, silicone
containing copolymers, thermoplastic elastomers, such as neoprene,
acrylonitrile butadiene copolymers, and combinations thereof.
[0076] Patterning the Plurality of Microspheres
[0077] In one embodiment, the plurality of microspheres may be
patterned using a patterned planar form such as a mesh or
perforated film, wherein a microsphere is held within each of the
openings or cavities of the patterned form. In one embodiment, the
patterned form is placed against a support and the plurality of
microspheres is flooded or cascaded onto the patterned form,
optionally using an excess amount of microspheres to ensure that
all openings or cavities are filled. An assisting member, such as a
doctor blade, felt wiper, brush having a plurality of bristles, a
vibration systems, a blower or air knife, vacuum, or combinations
thereof, may optionally be used to move, suck or agitate the
microspheres into each of the openings or cavities.
[0078] In another embodiment, the patterned form is a roller,
wherein the outer surface of the roller comprises a pattern of
cavities corresponding to the diameter of the microspheres. A
patterned roller is conducive to web processing, wherein the
plurality of microspheres floods the patterned roller. An assisting
member, as described above, may be used to ensure filling of the
cavities in the patterned roller.
[0079] In yet another embodiment, a patterned barrier material is
applied to a support. The barrier material is any suitable material
that substantially prevents microspheres from attaching to the
support on which the barrier material is applied. Exemplary barrier
materials include: waxes, resins, polymeric materials, inks,
inorganics, UV-curable polymers, and particles composed of either
organic or inorganic metallic or non-metallic materials. The
barrier material is applied in a predetermined pattern onto a
support. The barrier layer may be deposited by any suitable method.
Printing is typically the most preferred method, including contact
printing, e.g. flexographic printing, gravure printing, ink jet
printing, and screen printing. However, any discontinuous
deposition method (e.g. needle die coating of stripes) can be used.
The plurality of microspheres can be added to patterned barrier
material. The microspheres will be repelled by the patterned
barrier material and thus form a monolayer of patterned
microspheres. Such a technique is disclosed in WO Appl. No.
US2015/051864 filed 24 Sep. 2015, herein incorporated by
reference.
[0080] The patterned microspheres may then be contacted with a bead
bonding layer or a temporary support, such as an adhesive or a
transfer polymer layer, which temporarily retains the plurality of
microspheres in its microscopic pattern until they can be
transferred to a bead bonding layer.
[0081] In one embodiment, the patterned microspheres are contacted
directly with a bead bonding layer. For example, a plurality of
microspheres is contacted with a patterned roller comprising a
plurality of cavities. The microspheres fill the cavities and are
then transferred to a web comprising a bead bonding layer. The bead
bonding layer is in proximity (e.g., close proximity or contacting)
the microsphere-filled patterned roller, and the microspheres are
transferred to the bead bonding layer. To facilitate embedding of
the microspheres into the bead bonding layer, (1) the bead bonding
layer may be heated, (2) pressure may be applied between the
patterned roller and the web (e.g., via a nip configuration) or (3)
heating and applying pressure to the plurality of microspheres on
the bead bonding layer. Such a web process is described in WO Publ.
No. 2015/100220 (Culler et al.) incorporated by reference
herein.
[0082] In one embodiment, the decorative articles disclosed herein
may be made via a transfer process wherein the layer of
microspheres is patterned and held in a transfer resin which is
then used to transfer the layer of patterned microspheres onto the
bead bonding layer.
[0083] The transfer article of the present disclosure comprises a
monolayer of patterned microspheres which are attached, in some
embodiments partially embedded, in a transfer resin.
[0084] In one embodiment, the constructions of the present
disclosure are made via a transfer method, which may be understood
by reference to FIG. 5, which shows transfer article, which in its
simplest form, comprises support layer 59, transfer polymer layer
57 bonded thereto, and a plurality of patterned microspheres 51.
Transfer polymer layer 57 temporarily partially embeds the
plurality of microspheres. A bead bonding layer is constructed upon
the partially embedded microspheres optionally along with the
substrate layer. This construction may be accomplished by forming
the first bead bonding layer atop the transfer article and then
adding the substrate; or the decorative article may be made by
contacting the transfer article to a construction comprising the
substrate and the bead bonding layer and pressing the two together
such that the plurality of microspheres is embedded into the bead
bonding layer. The transfer polymer layer 57 has low adhesion to
the plurality of microspheres as compared to the bead bonding layer
in which the plurality of microspheres are also embedded in, so
that the support layer and transfer polymer layer can be removed to
expose the surface of the plurality of microspheres, generating the
decorative articles of the present disclosure. Such transfer
techniques are known in the art.
[0085] The transfer article comprises a support layer and a
transfer polymer layer. As will be described below, the
microspheres are first embedded into the transfer polymer layer of
the transfer article. Because the transfer polymer layer generally
has a tacky nature, the transfer polymer layer is typically
contacted onto a support layer to provide physical support.
[0086] The support layer should be "dimensionally stable". In other
words it should not shrink, expand, phase change, etc. during the
preparation of the transfer article. Useful support layers may be
thermoplastic, non-thermoplastic or thermosetting, for example. One
skilled in the art would be able to select a useful film for the
transfer article of the present disclosure. If the support layer is
a thermoplastic film it should preferably have a melting point
above that of the polymer used in the bead bonding layer. Useful
temporary support layers for forming the carrier include, but are
not limited to those selected from the group consisting of paper
and polymeric films such as biaxially oriented polyethylene
terephthalate (PET), polypropylene, polymethylpentene and the like
which exhibit good temperature stability and tensile so they can
undergo processing operations such as bead coating, adhesive
coating, drying, printing, and the like.
[0087] Useful materials for forming the transfer polymer layer
include, but are not limited to, thermoplastics such as those
selected from the group consisting of polyolefins such as
polyethylene, polypropylene, organic waxes, blends thereof, and the
like.
[0088] The thickness of the transfer polymer layer is chosen
according to the microsphere diameter distribution. According to
the present disclosure, the microsphere embedment becomes
approximately the mirror image of the transfer article embedment.
For example, a microsphere which is embedded to about 30% of its
diameter in the transfer polymer layer is typically embedded to
about 70% of its diameter in the bead bonding layer.
[0089] In order to partially embed the microspheres in the transfer
polymer layer, the transfer polymer layer should preferably be in a
tacky state (either inherently tacky and/or by heating). The
microspheres may be partially embedded, for example, by applying a
layer of microspheres on the transfer polymer layer followed by one
of (1)-(3):(1) heating the transfer article, (2) applying pressure
to the plurality of microspheres on the transfer article (with, for
example, a roller) or (3) heating and applying pressure to the
plurality of microspheres on the transfer article.
[0090] For a given transfer polymer layer, the microsphere
embedment process is controlled primarily by temperature, time of
heating and thickness of the transfer polymer layer. The interface
of the transfer polymer layer with the temporary support layer
becomes an embedment bonding surface since the microspheres will
sink until they are stopped by the dimensionally stable temporary
support layer.
[0091] The thickness of the transfer polymer layer should be chosen
to prevent encapsulation of most of the smaller diameter
microspheres so that they will not be pulled away from the first
polymer layer when the second polymer layer is removed. On the
other hand, the transfer polymer layer must be thick enough so that
the larger microspheres in the microsphere layer are sufficiently
embedded to prevent their loss during subsequent processing
operations.
[0092] The transfer article can be described using similar
properties as discussed above for the decorative article. In one
embodiment, the transfer article of the present disclosure, has a
ratio of microsphere height (h, defined as the vertical distance
from the microsphere apex to the transfer polymer surface) to
microsphere center-to-center distance (ctc) greater than 0.1, 0.15,
0.2, or even 0.25; and at most 0.4, 0.5, 0.8, or even 1. In one
embodiment, the plurality of microspheres cover more than 10, 15,
20, or even 25%; and less than 30, 40, 45, or even 50% of the
surface of the transfer polymer layer.
[0093] As described above, decorative articles, transfer articles
and methods of making them have been disclosed herein. Compared to
articles comprising a continuous monolayer of microspheres, the
articles of the present disclosure have an ordered, discontinuous
monolayer of microspheres as shown in FIG. 2. Less surface coverage
of the plurality of microspheres can allow for cost reductions
(e.g., less microspheres used per article, and/or article weighs
less). The microscopic periodic pattern of microspheres allows for
the entire microsphere coated surface of the decorative article to
have durability due to the protection afforded by the microspheres.
Ideally, the microscopic periodic pattern of microspheres has a
minimal amount of defects (e.g., missing microspheres, broken
microspheres). The ordered patterning of the plurality of
microspheres can enable benefits such as ease of cutting the
article (see, e.g., the straight line comprising no microspheres in
FIGS. 2 and 3) and/or the loss of microspheres along the cut line,
keeping the abrasion resistance and/or hardness of the article
maintained up to the cut line.
[0094] Exemplary embodiments of the present disclosure include, but
are not limited to
[0095] Embodiment 1. A decorative article comprising:
[0096] a microsphere layer comprising a plurality of microspheres,
wherein the microsphere layer comprises a monolayer of microspheres
and wherein the plurality of microspheres are in a microscopic
periodic pattern; and
[0097] a bead bonding layer disposed on the microsphere layer,
wherein the plurality of microspheres are partially embedded in the
bead bonding layer; and wherein the plurality of microspheres has a
ratio of microsphere height to microsphere center-to-center
distance greater than 0.1 and less than 0.5, and wherein the
decorative article has a coefficient of friction less than 0.3 as
measured by the Method for Coefficient of Friction Testing.
[0098] Embodiment 2. The decorative article of embodiment 1,
wherein the plurality of microspheres covers more than 10% and less
than 50% of the surface of the bead bonding layer,
[0099] Embodiment 3. A decorative article comprising:
[0100] a microsphere layer comprising a plurality of microspheres,
wherein the microsphere layer comprises a monolayer of microspheres
and wherein the plurality of microspheres are in a microscopic
periodic pattern; and
[0101] a bead bonding layer disposed on the microsphere layer,
[0102] wherein the plurality of microspheres are partially embedded
in the bead bonding layer; and wherein the plurality of
microspheres covers more than 10% and less than 50% of the surface
of the bead bonding layer, and wherein the decorative article has a
coefficient of friction less than 0.3 as measured by the Method for
Coefficient of Friction Testing.
[0103] Embodiment 4. The decorative article of embodiment 3,
wherein the plurality of microspheres has a ratio of microsphere
height to microsphere center-to-center distance greater than 0.1
and less than 0.5
[0104] Embodiment 5. The decorative article of any one of the
previous embodiments, wherein the plurality of microspheres covers
more than 20% and less than 30% of the surface of the bead bonding
layer.
[0105] Embodiment 6. The decorative article of any one of the
previous embodiments, further comprising a substrate, wherein the
bead bonding layer is disposed between the substrate and the
microsphere layer.
[0106] Embodiment 7. The decorative article of embodiment 6,
wherein the substrate comprises at least one of a metal, fabric,
polymer, paper, and combinations thereof.
[0107] Embodiment 8. The decorative article of any one of the
previous embodiments, wherein the decorative article has a pencil
hardness of at least 3H.
[0108] Embodiment 9. The decorative article of any one of the
previous embodiments, wherein the distance between nearest
neighbors in plurality of microspheres is 1/8 to 5 times the
average diameter of the microspheres.
[0109] Embodiment 10. The decorative article of any one of the
previous embodiments, wherein the plurality of microspheres have an
average diameter of 20 to 200 micrometers.
[0110] Embodiment 11. The decorative article of any one of the
previous embodiments, wherein the microscopic periodic pattern
comprises a repeat unit selected from: triangular, quadrilateral,
pentagonal, hexagonal, and combinations thereof.
[0111] Embodiment 12. The decorative article of any one of the
previous embodiments, wherein the microspheres in the plurality of
microspheres are translucent or opaque.
[0112] Embodiment 13. The decorative article of any one of the
previous embodiments, wherein the microspheres in the plurality of
microspheres comprise at least one of a glass, ceramic, glass
ceramic, metal, plastic, and combinations thereof.
[0113] Embodiment 14. The decorative article of any one of the
previous embodiments, wherein the microspheres in the plurality of
microspheres have a Knoop hardness of 1300 kg/m.sup.2.
[0114] Embodiment 15. The decorative article of any one of the
previous embodiments, wherein the microspheres in the plurality of
microspheres have an index of refraction of less than 1.55.
[0115] Embodiment 16. The decorative article of any one of the
previous embodiments, wherein the microspheres in the plurality of
microspheres have a sphericity of at least 80%.
[0116] Embodiment 17. The decorative article of any one of the
previous embodiments, wherein the microspheres in the plurality of
microspheres have a size difference of no more than 40%.
[0117] Embodiment 18. The decorative article of any one of the
previous embodiments, wherein the bead bonding layer comprises at
least one of: a polyurethane, polyesters, (meth)acrylic acid ester
polymers, an epoxy, a (meth)acrylate, polyvinylchloride polymer,
polyvinyl acetate polymer, polyamides, a urethane/(meth)acrylate, a
silicone, polyolefin, fluoropolymers, acrylobutadiene polymers, and
blends thereof.
[0118] Embodiment 19. The decorative article of any one of the
previous embodiments, wherein the monolayer of microspheres further
comprises a macroscopic pattern.
[0119] Embodiment 20. The decorative article of any one of the
previous embodiments, comprising a crosslinked polymer, a
fluoropolymer, and combinations thereof.
[0120] Embodiment 21. A transfer article comprising:
[0121] a support layer;
[0122] a transfer polymer layer bonded to the support layer;
and
[0123] a microsphere layer comprising a plurality of microspheres,
wherein the microsphere layer comprises a monolayer of microspheres
and wherein the plurality of microspheres are in a microscopic
periodic pattern; and wherein the plurality of microspheres are
partially embedded in the transfer polymer layer such that more
than 50% of the average diameter of the microspheres is exposed and
the plurality of microspheres covers more than 10% and less than
50% of the surface of the transfer polymer layer.
[0124] Embodiment 22. A transfer article comprising:
[0125] a support layer;
[0126] a transfer polymer layer bonded to the support layer;
and
[0127] a microsphere layer comprising a plurality of microspheres,
wherein the microsphere layer comprises a monolayer of microspheres
and wherein the plurality of microspheres are in a microscopic
periodic pattern; and wherein the plurality of microspheres are
partially embedded in the transfer polymer layer such that more
than 50% of the average diameter of the microspheres is exposed and
wherein the plurality of microspheres has a ratio of microsphere
height to microsphere center-to-center distance greater than 0.1
and less than 0.5.
[0128] Embodiment 23. The method of any one of embodiments 21-22,
wherein the transfer polymer layer comprises at least one of a
polyolefin, organic wax, and combinations thereof.
[0129] Embodiment 24. A method of making a decorative article, the
method comprising:
[0130] spatially orienting a plurality of microspheres in a layer,
such that the plurality of microspheres has a microscopic periodic
pattern;
[0131] embedding the layer of microspheres in a transfer
polymer;
[0132] contacting the embedded layer of microspheres with a bead
bonding layer; and
[0133] removing the transfer polymer to form the decorative article
of any one of embodiments 1-20.
[0134] Embodiment 25. The method of embodiment 24, wherein the
plurality of microspheres are spatially oriented using a mesh
comprising a plurality of openings to hold a microsphere and a
vacuum to pull the plurality of microspheres to the mesh.
[0135] Embodiment 26. A method of making the decorative article of
any one of embodiments 1-20, comprising:
[0136] depositing a barrier layer material in a predetermined
pattern onto a first major surface of a support to form a patterned
barrier layer;
[0137] contacting a plurality of microspheres onto the patterned
barrier layer to form a patterned microsphere layer;
[0138] contacting the patterned microsphere layer with a transfer
polymer and removing the support to form an embedded layer of
microspheres comprising a plurality of microspheres partially
embedded in the transfer polymer with the apexes of the
microspheres exposed;
[0139] contacting the exposed apex side of the embedded layer of
microspheres with a bead bonding layer; and
[0140] separating the bead bonding layer from the transfer polymer
to form the decorative article of any one of embodiments 1-20.
[0141] Embodiment 27. A method of making the decorative article of
any one of embodiments 1-20, comprising:
[0142] depositing a barrier layer material in a predetermined
pattern onto a first major surface of a support to form a patterned
barrier layer;
[0143] contacting a plurality of microspheres onto the patterned
barrier layer to form a patterned microsphere layer;
[0144] contacting the patterned microsphere layer with a bead
bonding layer; and
[0145] removing the support to make the decorative article of any
one of embodiments 1-20.
[0146] Embodiment 28. A method of making the decorative article of
any one of embodiments 1-20, comprising:
[0147] providing a production tool having a plurality of cavities,
wherein the plurality of cavities are in a predetermined
pattern;
[0148] contacting a plurality of microspheres to the production
tool such that the plurality of cavities are filled with the
plurality of microspheres to form a layer of patterned
microspheres;
[0149] transferring the layer of patterned microspheres to a
transfer polymer to form an embedded layer of microspheres
comprising a plurality of microspheres partially embedded in the
transfer polymer with the apexes of the microspheres exposed;
[0150] contacting the exposed apex side of the embedded layer of
microspheres with a bead bonding layer; and
[0151] separating the bead bonding layer from the transfer polymer
to form the decorative article of any one of embodiments 1-20.
[0152] Embodiment 29. A method of making the decorative article of
any one of embodiments 1-20, comprising:
[0153] providing a production tool having a plurality of cavities,
wherein the plurality of cavities are in a predetermined
pattern;
[0154] contacting a plurality of microspheres to the production
tool such that the plurality of cavities are filled with the
plurality of microspheres to form a layer of patterned
microspheres;
[0155] transferring the layer of patterned microspheres to a bead
bonding layer to form an embedded layer of microspheres comprising
a plurality of microspheres partially embedded in the bead bonding
layer to make the decorative article of any one of embodiments
1-20.
EXAMPLES
[0156] Advantages and embodiments of this disclosure are further
illustrated by the following examples, but the particular materials
and amounts thereof recited in these examples, as well as other
conditions and details, should not be construed to unduly limit
this invention. In these examples, all percentages, proportions and
ratios are by weight unless otherwise indicated.
[0157] All materials are commercially available, for example from
Sigma-Aldrich Chemical Company; Milwaukee, Wis., or known to those
skilled in the art unless otherwise stated or apparent.
TABLE-US-00002 Designation Description K-FLEX 188 100% active
polyester polyol obtained from King Industries, Inc., Norwalk, CT
under trade designation "K-FLEX 188" DESMODUR Solvent-free
polyfunctional aliphatic isocyanate resin based on N3300A
hexamethylenediisocyanate, obtained from Bayer Materials Science,
Pittsburgh, PA under trade designation "DESMODUR N3300A" T12
Catalyst, dibutyltin dilaurate (DBTDL), a liquid catalyst, Air
Products and Chemicals, Inc., Allentown, PA under trade designation
"DABCO T-12" RDL Beads Non-vitreous, solid, transparent ceramic
microspheres made according to the teachings of U.S. Pat. No.
4,564,556 ZGC Beads Ceramic microspheres, obtained from 3M Company,
Saint Paul, MN under trade designation "3M MICRO MILLING MEDIA
ZGC-75" and "3M MICRO MILLING MEDIA ZGC-100", respectively
Polyethylene A 1 mil (25 micrometer), 2 mil (50 micrometer), or 4
mil (100 micrometer) Transfer Liner polyethylene film extrusion
coated onto 3.8 mil (96.5 micrometer) polyethylene teraphtalate
(PET) 3M Tape 1280 Low stretch polyester tape, obtained from 3M
Company, Saint Paul, MN under trade designation "3M CIRCUIT PLATING
TAPE 1280" n-Heptane Obtained from Aldrich Chemical Company,
Milwaukee, WI SPG Print Obtained from SPG Prints America Inc.,
Charlotte, NC Screens
[0158] Test Methods
[0159] Method for Determining Pencil Hardness
[0160] Samples were prepared according to the Examples and
Comparative Examples described below were evaluated for pencil
hardness according to ASTM D 3363-00 "Standard Test Method for Film
Hardness by Pencil Test". Abrasive sandpaper (Grit No. 400) was
adhered to a flat and smooth benchtop with double coated tape.
Pencil leads (Totiens Drawing Leads with mechanical lead holder)
were held at an angle of 90.degree. to the abrasive paper and
abraded until a flat, smooth, circular cross-section free of chips
or nicks on the edge of the lead was achieved. The force on the tip
of the pencil was fixed at 2.5 N. The sample was placed on a glass
surface. Using a freshly prepared pencil lead for each test, the
lead was pressed firmly against the sample at a 45.degree. angle
and at the desired load (2.5 N) using an Elcometer 3086 Motorized
Pencil Hardness Tester (obtained from Elcometer Incorporated,
Rochester Hills, Mich.) and drawn across the test panel in the
"forward" direction for a distance of at least 1/4 inch (6.4 mm).
Three pencil tracks were made for each grade of lead hardness.
Prior to inspection, crumbled lead was removed from the test area
using a damp paper towel wetted with isopropyl alcohol. The sample
was inspected by eye for defects for the first 1/8 (3.2 mm) to 1/4
inch (6.4 mm) of each pencil track. Moving from harder leads to
softer, the process was repeated down the hardness scale until a
pencil was found that did not scratch the sample or rupture it, or
dislodge or partially dislodge any microspheres. At least two of
three tracks at each lead hardness were required to meet these
criteria in order to pass. The hardest level of lead that passed
was reported as the pencil hardness for the sample.
[0161] Method for Taber Abrasion Test
[0162] Abrasion testing was carried out using a linear Tabor
Abrasion Tester (obtained from Taber Industries, North Tonawanda,
N.Y.). The samples prepared according to the Examples and
Comparative Examples described below were fixed to the testing
surface and abraded with a CS-10 wearaser with 408 grams weight,
500 cycles at 25 cycles/minute. Samples were evaluated for
microsphere damage, microsphere displacement and damage between
microspheres. Also, the samples were rated (from 1-5, with 5 being
the most damage) for the level of damage attained by the sample
during Taber abrasion testing.
[0163] Method for Profilometry Measurements
[0164] Microsphere height, average microsphere height, microsphere
diameter at the surface of samples prepared according to the
Examples and Comparative Examples described below were determined
from profilometry using a Bruker Dektak XT profiler (obtained from
Bruker Corp., Billerica, Mass.). Measurement setup, instrument
operation, and data analysis were performed using Bruker Vision64
software (obtained from Bruker Corp., Billerica, Mass.). The
parameters used for surface measurements of the samples were as
follows: [0165] Scan Type: Map Scan; Range: 524 .mu.m; Profile:
Hills and Valleys; Stylus Type: 2 .mu.m; [0166] Style Force: 5 mg;
Length: 1000 .mu.m; Duration: 10 sec; Resolution: 0.333 .mu.m/pt;
[0167] Sample: 3001 pts; Speed: 100 .mu.m/s; Map Extent: 200 .mu.m;
Map resolution: 5 .mu.m/trace; [0168] Number of traces: 40;
Additional Parameters: Soft touchdown and safe mode.
[0169] Samples prepared according to the Examples and Comparative
Examples described below were prepared by applying a section of
gloss finish transparent tape to the sample surface to be used as
the landing spot and starting point for each trace. The flat
surface created by the gloss tape allowed for more accurate
stitching of traces to produce a 3D map of the sample surface.
[0170] The data analyzer recipe contained Mask Data and Remove Tilt
filters and Z stats to obtain the Rpm (average peak height)
calculation. The measured microsphere height and diameter at the
sample surface was determined by averaging the x and y coordinates
from 3 individual traces to determine the height of the sample
floor, the maximum height of the microsphere, and the diameter of
the microsphere at the sample surface.
[0171] Method for Coefficient of Friction Testing
[0172] Samples prepared according to the Examples and Comparative
Examples described below were evaluated for coefficient of friction
using a table top peel tester (Model 3M90, available from
Instrumentors Inc., Strongsville, Ohio). A 3.2 mm (0.013 inch)
thick elastomeric foam having a density of about 0.25 g/cc (cubic
centimeters) was bonded to a flat steel substrate measuring 63.5 mm
(2.5 inches) square, having a thickness of about 6 mm (0.024
inches), and weighing approximately 200 grams including the foam.
Next, a sample having a length of 63.5 mm (2.5 inches) that was
approximately 5 mm longer than the steel substrate was place over
the foam covered surface of the steel substrate such that the
sample was wrapped around the leading edge of the steel substrate.
A hole was cut in the sample to accommodate the pin by which the
steel substrate was pulled during testing. This test article was
placed with the sample side down on an isopropyl alcohol wiped
glass surface measuring at least 15.2 cm by 25.4 cm (6 inches by 10
inches). A table top peel tester was used in the coefficient of
friction mode to pull the test article across the glass surface at
a rate of about 2.29 meters/minute (90 inches/minute) for at least
about 5 seconds, wherein the surface comprising the plurality of
microspheres (if present) contacted the glass surface. The
transducer was calibrated with the force from the weight of the
steel substrate with foam as 1.00. In this way pulling forces were
directly read out as coefficient of friction (COF). The dynamic
(kinetic) coefficient of friction was determined by evaluating the
graph of the COF values beginning one second after the start of the
measurement. Data was collected at a rate of ten readings/second
and the average was recorded. Three trials were run for each sample
and the average was reported for the coefficient of friction.
[0173] Method for Retro-Reflectivity Test
[0174] Measurements of the coefficient of retro-reflection (Ra)
were made directly on the surface comprising the plurality of
microspheres of various constructions prepared according to the
Examples and Comparative Examples described below. Procedure B of
10 ASTM Standard E 809-94a (2000) "Standard Practice for Measuring
Photometric Characteristics of Retroreflectors" was followed. The
samples were measured at an entrance angle of -4.0 degrees and an
observation angle of 1 degree. The photometer used for those
measurements was Model Retro-Meter 2 available from Advanced
Retrotechnology Inc., Baltimore, Md. Ra was reported in
Candelas/square meter/lux.
[0175] Method for Microscopy Test
[0176] Microscopic distance measurements were conducted using a
Nikon Optophot 66 microscope (obtained from Nikon Corp., Tokyo,
Japan) with a Paxcam II digital camera (obtained from PAXCam,
VillaPark, Ill.) connected to a personal computer. The Paxcam II
software was calibrated with a microscopic scale allowing the
determination of microsphere size and distance between microspheres
using transmitted light through the samples. Software allowed
precise measurements of microsphere size and calculation of the
coverage of microspheres on the surface. This calculation was based
upon exposed particle area from profilometer data and distance
between microspheres from microscope measurements. For the
patterned microsphere samples, the percent coverage of the surface
is equal to the ratio of the exposed area projection of 3
microspheres to the area of the hexagonal unit cell. For the random
(or unpatterned) samples, the percent coverage was measured by
using ImageJ image analysis software, available at ImageJ.net
website, which counts particles, measures sizes and the total
coverage of the surface. The measurements were corrected by the
exposed area projection of the microspheres.
[0177] Method for Preparing Microsphere-Coated Articles
[0178] Patterning of the Microsphere Monolayer
[0179] Microspheres to be coated were sieved using screen sieves to
produce a relatively narrow size distribution. The sieves were
obtained from Tyler Inc., Mentor, Ohio. ZGC 100 beads were sieved
to between 90 and 106 micrometers, ZGC 75 beads were sieved to
between 75 and 90 micrometers and RDL beads were sieved to between
160 and 190 microns. Then, round beads were separated from
irregular beads with flat spots or broken beads using a Roundometer
(obtained from Future Labs LLC, Madison Miss.) with a plate at a 3
degree angle. Round beads were used for coating while the irregular
beads were discarded.
[0180] SPG Print Screens were used as positioning (i.e.,
patterning) screens. Five different screens were used varying in
hole sizes and hole center to center (CTC) distance as follows:
TABLE-US-00003 Hole center to center Hole Size distance Screen #
(micrometers) (micrometers) 0 67 154 1 67 123 2 101 320 3 53 130 4
120 428
[0181] The patterning screens were placed upon a supporting 1/8
inch (3.2 mm) media grade 5, porous stainless steel (obtained from
Mott Corporation, Farmington, Conn.) pieces cut to small 3 inch by
5 inch (7.6 cm.times.12.7 cm) pieces for the Examples and
Comparative Examples described below. The support plate and
patterning screen were fitted over a funnel connected to a vacuum
source to create a pull on the microspheres as they sat on top of
the holes in the screens. The vacuum was generated using a 2-HP
Craftsman vacuum (obtained from a Sears department store).
Microspheres were placed on the patterning screens by brushing a
small pile of microspheres over the screen surface with a small
paint brush while applying the vacuum to the assembly.
[0182] After the microspheres were placed on the patterning screen
as described above, 3M Tape 1280 was placed on the patterning
screen, contacting the microspheres. After applying a roller over
the microspheres, the vacuum air flow was stopped and the tape was
peeled off the patterning screen. Essentially all of the
microspheres were transferred from the patterning screen to the
tape in a regular pattern as determined by the patterning
screen.
[0183] Preparation of Patterned Microsphere Monolayer Transfer
Article
[0184] The monolayer of microspheres on the 3M Tape 1280 (from
above) was pressed against a polyethylene transfer liner film
(selected from 1 mil (25 micrometer), 2 mil (50 micrometer), or 4
mil (100 micrometer) thick polyethylene on 3.8 mil (96.5
micrometer) polyester film), with the application of moderate heat
at 130.degree. C. for a short time partially imbedding the
microspheres into the polyethylene. After allowing the sandwich
assembly for several minutes to allow at least partial
crystallization of polyethylene around the microspheres, the tape
was removed by applying n-heptane to the interface between the tape
and the microspheres. The heptane dissolved the tape adhesive and
resulted in a clean transfer of the microspheres to the
polyethylene liner film. The microsphere-coated polyethylene sheet
was further rinsed with heptane and allowed to dry. The
microsphere-coated sheet was then heated in an oven at 135C for
various times in order to "sink" the microspheres in the
polyethylene layer. The sinking was accomplished either at 2
minutes in the oven for some of the microspheres or 6 minutes for
some of the larger microspheres to form a transfer article.
[0185] Preparation of Random Microsphere Monolayer Transfer
Article
[0186] 25 grams of microspheres were placed in a metal box with a
lid. On the lid was taped the polyethylene transfer liner 6 inch by
8 inch (15 cm.times.20.3 cm) in size. The box and the liner were
heated to 105.degree. C. for 0.5 hours in an oven. The box was
turned upside down to deliver the warm microspheres to the surface
of the polyethylene liner while the box was tilted back to front,
side to side, and corner to corner, so as to uniformly cascade the
mass of microspheres across the surface of the liner. After
approximately 1 minute the box was turned back upside down and the
lid was tapped to remove loose microspheres on the liner. The
coated liner and lid was removed and placed in an oven at
135.degree. C. for 2 minutes to fully sink the micropheres in the
polyethylene layer to form a transfer article. The transfer article
comprised a random ordering of microspheres on the surface of the
transfer article.
[0187] Preparation of a Decorative Article
[0188] The transfer article (from above) was then taped to a
silicone coated polyester release liner and the exposed
microspheres were overcoated with a 5 mil thick (127 micrometers)
two-part urethane coating with a polyester substrate (3-mil thick
(76.2 micrometer)), which were applied simultaneously using a notch
bar coater. The two-part polyurethane was prepared by mixing
DESMODUR N3300 polyisocyanate (10 grams) and KFLEX K188 polyol
(12.04 grams) in a ratio giving a 5% excess of isocyanate groups
(Index 1.05). A T-12 catalyst (67 microliters) was added together
with other components and mixed in a FlackTek Speedmixer DAC 150
FV; both from Flac Tec Incorporated, Landrum, S.C. at 3450 rpm for
30 seconds:. The polyurethane-coated multilayered article was cured
in an oven at 70.degree. C. for 1 hour and set aside for 24 hours.
The multilayered article was pulled apart between the polyethylene
and polyurethane layers, exposing the plurality of microspheres now
embedded in the polyurethane layer. The resulting decorative
article had an ordered mono-layered array of microspheres partially
embedded (>50%) in a tough, hard polyurethane film with a 3-mil
thick (76.2 micrometer) polyester substrate disposed on the
opposing surface of the polyurethane layer.
Examples 1 and 1A (EX1-EX1A)
[0189] EX1 was a patterned microsphere-containing article prepared
according to the Preparation of Patterned Microsphere Monolayer
Transfer Article using SPG Print Screen #0 and ZGC 100 beads. The
polyethylene transfer liner was 1 mil (25 micrometer) thick
polyethylene layer on 3.8 mil (96.5 micrometer) polyester film with
a 2 minute sink time.
[0190] EX1A was prepared by per the Preparation of a Decorative
Article using EX1 as the transfer article. The top surface of EX 1A
was analyzed following the Method for Profilometry Measurements and
FIG. 2 is the schematic representation of those results.
Examples 2 and 2A (EX2-EX2A)
[0191] EX2 and EX2A were prepared in the same manner as EX1 and
EX1A, respectively, except that an SPG Print Screen #1 and ZGC 75
beads were used.
Examples 3 and 3A (EX3-EX3A)
[0192] EX3 and EX3A were prepared in the same manner as EX2 and
EX2A, respectively, except that an SPG Print Screen #3 was
used.
Comparative Examples 4 and 4A (CEX4-CEX4A)
[0193] CEX4 was a random microsphere-containing article prepared
according to the Preparation of Random Microsphere Monolayer
Transfer Article using ZGC 75 beads. The polyethylene transfer
liner was a 2-mil (50 micrometer) thick polyethylene layer on
3.8-mil (96.5 micrometer) thick polyester film and a sink time of 2
minutes was used.
[0194] CEX4A was prepared by per the Preparation of a Decorative
Article using EX4 as the transfer article.
Comparative Examples 5 and 5A (CEX5-CEX5A)
[0195] CEX5 and CEX5A were prepared in the same manner as CEX4 and
CEX4A, respectively, except that ZGC 100 beads were used.
Examples 6 and 6A (EX6-EX6A)
[0196] EX6 and EX6A were prepared in the same manner as EX1 and
EX1A, respectively, except that an SPG Print Screen #2 and RDL
beads were used.
Examples 7 and 7A (EX7-EX7A)
[0197] EX7 and EX7A were prepared in the same manner as EX6 and
EX6A, respectively, except that polyethylene transfer liner having
2-mil (50 micrometer) thick polyethylene layer on 3.8-mil (96.5
micrometer) thick polyester film and a sink time of 6 minutes was
used.
Examples 8 and 8A (EX8-EX8A)
[0198] EX8 and EX8A were prepared in the same manner as EX7 and
EX7A, respectively, except that polyethylene transfer liner having
4-mil (100 micrometer) thick polyethylene layer on 3.8-mil (96.5
micrometer) thick polyester film was used.
Comparative Examples 9 and 9A (CEX9-CEX9A)
[0199] CEX9 and CEX5A were prepared in the same manner as EX6 and
EX6A, respectively, except that SPG Print Screen #4 was used.
Comparative Examples 10 and 10A (CEX10-CEX10A)
[0200] CEX10 and CEX10A were prepared in the same manner as CEX9
and CEX9A, respectively, except that polyethylene transfer liner
having 2-mil (50 micrometer) thick polyethylene layer on 3.8-mil
(96.5 micrometer) thick polyester film and a sink time of 6 minutes
was used.
Examples 11 and 11A (EX11-EX11A)
[0201] EX11 and EX11A were prepared in the same manner as EX8 and
EX8A, respectively, except that SPG Print Screen #4 was used.
Comparative Example 12 (CEX12)
[0202] CEX12 was a two-part polyurethane film coated on a 3-mil (75
micrometer) polyester film. The polyurethane had the same
formulation as that used for overcoating described in the
Preparation of a Decorative Article described above.
Comparative Example 13 (CEX13)
[0203] CEX13 was a 3-mil thick polyester film.
Comparative Example 14 and 14A (CEX14-CEX14)
[0204] CEX14 and CEX14A were prepared in the same manner as CEX4
and CEX4A, respectively, except that RDL beads were used, and the
polyethylene transfer liner was a 4-mil (100 micrometer) thick
polyethylene layer on 3.8-mil (96.5 micrometer) thick polyester
film and a sink time of 6 minutes was used.
[0205] The examples and comparative examples were characterized
using the test methods described above and the results are shown in
Tables 1-2. Shown in Tables 1 and 2 are the average microsphere
diameter which was determined by viewing the RDL beads and ZGC
beads (unbedded) under a microscope and taking the average of three
microspheres. The average distance between the apex of the
microspheres (ctc) in the examples and comparative examples was
determined by the Method for Microscopy Test using at least three
different pairs of microspheres. The average microsphere height (h)
in the examples and comparative examples was measured looking at
the average of at least three microspheres using the Method for
Profilometry Measurement. The average microsphere height (h) was
divided by the average distance between ratio the apex of the
microspheres (ctc) to determine the h:ctc ratio. The measured
microsphere diameter at polymer surface was calculated as follows.
The examples and comparative examples were analyzed using the
Method for Profilometry Measurement to determine the height of the
microsphere from the polymer surface (e.g., bead bonding layer).
Knowing this data and the diameter of the microspheres initially
used, the microsphere diameter at the polymer surface was
calculated. The percent surface coverage of the microspheres was
determined by using the microsphere diameter at polymer surface and
calculating the surface area of the microsphere and dividing this
value by the total surface area. Pencil hardness was determined
following the Method for Determining Pencil Hardness. Friction
coefficient was determined following the Method for Coefficient of
Friction Testing. Ra was determined following Method for
Retro-Reflectivity Test. Taber abrasion was determined following
Method for Taber Abrasion Test. N/A used in the tables means not
applicable.
TABLE-US-00004 TABLE 1 Example EX1A EX2A EX3A CEX4A CEX5A EX6A EX7A
Microsphere used ZGC 100 ZGC 75 ZGC 75 ZGC 75 ZGC 100 RDL RDL
Description patterned patterned patterned random random patterned
patterned Average Microsphere 100 80 80 80 100 160 160 Diameter,
.mu.m ctc, .mu.m 151 123 131 N/A N/A 310 310 h, .mu.m 19.8 23.1
17.9 19.1 17.1 18.8 32.7 h:ctc ratio 0.13 0.19 0.14 N/A N/A 0.06
0.11 Microsphere Diameter 81.20 76.40 71.40 70.8 73.70 109.25
135.50 at Polymer Surface, .mu.m Surface Coverage, % 27.37 30.42
24.60 0.0 0.0 11.40 16.03 Pencil Hardness 10H 10H 10H 10H 10H 6H 8H
Friction Coefficient 0.10 0.09 0.09 0.14 0.13 0.10 0.13 Ra
Candelas/square 0.09 0.24 0.19 0.12 0.13 0.18 0.17 meter/lux Taber
Abrasion 2 2 2 1 1 3.5 2.5
TABLE-US-00005 TABLE 2 Example EX8A CEX9A CEX10A EX11A CEX12 CEX13
CEX14A Microsphere used RDL RDL RDL RDL Film Film RDL Description
patterned patterned patterned patterned N/A N/A random Average
Microsphere 160 160 160 160 N/A N/A 160 Diameter, .mu.m ctc, .mu.m
310 407 405 405 N/A N/A 188 h, .mu.m 66.3 21.1 31.9 58 N/A N/A 49.6
h:ctc ratio 0.21 0.05 0.08 0.14 N/A N/A 0.26 Microsphere Diameter
178.80 116.40 133.90 171.60 N/A N/A 158 at Polymer Surface, .mu.m
Surface Coverage, % 22.21 6.97 9.23 12.48 N/A N/A 63.7 Pencil
Hardness 10H 2H 2H 4H 4B 8B 10H Friction Coefficient 0.12 0.14 0.13
0.13 N/A 0.13 0.13 Ra Candelas/square 0.17 0.16 0.21 0.19 N/A N/A
0.27 meter/lux Taber Abrasion 1.5 4 2.5 3 5 5 1
[0206] Foreseeable modifications and alterations of this invention
will be apparent to those skilled in the art without departing from
the scope and spirit of this invention. This invention should not
be restricted to the embodiments that are set forth in this
application for illustrative purposes. To the extent that there is
a conflict or discrepancy between this specification and the
disclosure in any document incorporated by reference herein, this
specification will control.
* * * * *